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  1. #1
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    Exclamation New Shingle Roof Installed looks like a wavy ocean ?

    Hello from New Zealand , can I please have some advice on what I should do next ?
    Our new Roof has just been put on new House[ certainteed tiles on plywood on trusses ] , noticed some strange shaddowing on roof day after it was installed [ have attached a photo ]
    Installers used 15mm Tongue and groove untreated ply , trusses are 900mm spacings , heres the kicker when roof was being installed we had alot of rain some of ply and rubber underlay mat would have got wet before shingles applied . Also plywood was freshly milled and was wrapped in plastic and sat outside for a week , we noticed some sweating under plactic when they starting using ply we mentioned this to Installers and they said no issue at all [ some ply even had slight green mold on edges of sheets ] installers said no issue to this also !
    As you can see we have a problem Can this be fixed or will roof need to be replaced [ note roof is 580 square metres ! size ]
    We havent paid for job done or materials yet [ on our lawyers advice ] what would you recommend we do ? [ the tiles themselves do look great , but only when sun not shining ] thank you

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  2. #2
    Darrel Hood's Avatar
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Of course I know nothing about New Zealand's laws, but if this occurred in my area, I would withhold payment until it was properly corrected.

    Darrel Hood
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  3. #3
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Around here.......the builder would have a sick feeling in the pit of his stomach and rightly so, cuz he's gonna be redoing that roof.

    If you choose not to decide, you still have made a choice.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    It is rare that someone finds themselves in your situation (having not paid for the material or labor (yet)). My first recommendation is to follow your lawyer's advice and don't pay for the job not well done. My next recommendation is to tell these guys to remove their material and get lost , or you will have it done on their behalf... and back charge them for your trouble... including the cost of your family finding alternative housing while the work is being done.

    Now it may have been OK to install the plywood wet, as far as they are concerned; but I would not have allowed it on my home. There is a saying in the construction industry regarding quality control that goes something like this; "I can't see it from my [their] house".

    Beside trapping the moisture (which is great for festering mold and decay), roof sheathing is supposed to be installed relatively dry, with a gap between the sheets to allow for expansion. Unless specified otherwise by the manufacturer; 1/8" is standard. If the tongues and grooves were beaten together (with a wood block), and those joints are beaten tight (which is even worse); you are likely going to get buckling. Well, you've got buckling.

    Now the roofer may blame it on the carpenter (if they are different contractors), but the roofer should not have installed his product on the deck if there was a problem. Since he accepted it, he is at the very least part owner of the problem. I think your lawyer should contact 3 people; the roofer, the carpenter, and ultimately the general contractor.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    "...installers said no issue..." guess not they are paid to do job. To come back would mean no pay for that day.

    Is that the GC lower right with red face ?

    Correction needed. Replacing the deck is the answer.
    Hold the money.
    Fire up your attorney.
    Be prepared for a fight.
    Do not wast any time to get the process going. It may be a long fight.
    I think any Judge would be sympathetic to your case if it get that far.
    Though the GC argument is that it is cosmetic not structural.


  6. #6
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Personally, like others said, I would have it redone. Downside is you might have to let them try and fix it right, otherwise you might have to burden the cost of another contractor removing the "old" roof to install the "new" roof. I think it would be real tough to get money for the removal of the "old" roof.

    If you look at the sheathing from below do you see H-clips between the plywood joints between the trusses? If no H-clips, or any kind of space/gap, you can probably assume no room for expansion and thus the resulting buckling.

    No idea about your laws, but like Garry said you might have a long fight with this and you might have a lien tossed on the home. The builder will probably say nothing wrong with it structurally, but I'm sure the manufacturers (roofing/sheathing) will not warrantee anything as it is not installed properly, so you have that to fall on, might want to contact them.

    On a side note, anyone else see plywood show up wrapped in plastic on jobsites. I have seen tarps over the top to keep rain off, and that's rare, but not wrapped in plastic???


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Thanks very much for all your replies I am learning all the time , hinsight if I had studied this roofing idea and materials more closely before beginning the build I would have went for a simple tin roof . Hinsight a great thing !!!!!!!
    To answer some of your questions : The main builder on the construction has been great to deal with and is a family friend . The Roof job and materials was subed out to another Roofing company , to be fair they have also been good to deal with , but this may change if roof issue not sorted soon [ as I said earlier they havent been paid at all , but Main Builder has been ] .
    You have asked if H clips were used ? , sorry I dont know what these are ? But I cant see any clips . The 15mm tongue and grove untreated ply was nailed to Trusses [ did note that ply was hit together tight , no gap between sheets and no clips ? ] .
    Yes stack/pallet loads of plywood about 1 metre high was wrapped in plastic and left out side ?
    The arguement that roof is still structrial sound and problem is only cosmetic makes me really mad ! , if I was after a roof not for its look just to stop water coming in I would have tied a hay cover up there , and not cared what it looked like ! !
    Roofing contractor did say that Roofing job has been done to NZ specifications?
    Thanks again I really appreciate and need your advice


  8. #8
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    The OP stated that 19mm (3/4")T&G was used on decking.
    H clips are not used on T&G.
    Also stated that it rained on decking before applying shingles was finished.

    Most likely, underlayment is wrinkled.

    Correction
    Tear off shingles and underlayment in affected areas and replace.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Pete, What are you calling the "roofing job"? You have two different "jobs" going on there. One "job" is the installation of the plywood, which is where the fault lies. The other "job" is the installation of the shingles. Although there may be some [other] faults with the shingles, they are not the subject of this thread.

    In other words; the waves that you notice in the shingles are a symptom. The cause of the symptom of the plywood beneath the shingles buckling.

    Naturally the builder is going to say the roofing job has been done to NZ specs, but as I stated; the shingles are not the problem, they are the symptom. I wish them luck trying to correct the plywood sheathing without removing all of the shingles.

    On another note let me tell you that you have received some very good advice on this thread. BUT please allow your lawyer to do his job. I doubt that any judge will accept the argument "NZ specs" spiel and expect you to have that roof forced on you. Besides being unsightly, it has a direct impact on the value of the home. But then again, I am not a lawyer either.

    The only other advice I can give you is to make sure your lawyer has plenty of construction litigation experience. I think I would also consider including the shingle manufacturer, the lumber yard, and anyone else that has a connection to the roof.

    See if you have a "Jerry Peck" in your area. A good "Jerry Peck" may be beneficial.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Any pictures from the attic of the decking which would show tongue and groove areas and of the trusses?

    Does NZ have a new home warranty program in which the builder must be registered builder and the quality of the build is dictated by the new home warranty program?

    15 mm is the equivalent of 1/2" plywood.

    As Rick noted it very well could be the underlayment.


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by Raymond Wand View Post
    15 mm is the equivalent of 1/2" plywood.
    I don't know why I wrote 19mm

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Rick

    Didn't even notice your measurement of 19mm, was looking at the original posters measurement.


    Cheers,


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    15 mm is closer to 5/8", no? It is greater than 1/2".

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    John
    My conversion table shows
    15mm = 0.59055118 inches
    So yes 5/8 and not half inch.
    Thanks for catching that.

    Last edited by Raymond Wand; 05-26-2013 at 06:52 PM.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by Rick Cantrell View Post
    The OP stated that 19mm (3/4")T&G was used on decking.
    H clips are not used on T&G.

    Yeah, now I remember reading that, went on a tangent of what could be wrong, but yup, you won't find any H-clips with the T&G, apologies to David for making him look or confusing the issue...


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Another thing : The Roofers have suggested that the wavy roof will come right in summer [ another 5 months away ] as tiles will heat and settle and the ply should straighten itself with heat ? , it is winter here now with frosts . I could`nt amagine ply straightening it`s self with heat ? But I`m no expert ! but I`m not a flamen idiot either !


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by david millar View Post
    Another thing : The Roofers have suggested that the wavy roof will come right in summer [ another 5 months away ] as tiles will heat and settle and the ply should straighten itself with heat ? , it is winter here now with frosts . I could`nt amagine ply straightening it`s self with heat ? But I`m no expert ! but I`m not a flamen idiot either !
    When they told you this, did you feel a pulling sensation on your leg?

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    In 5 months the sub that did the decking will have lowered their periscope and will be in the silent running mode.


  19. #19
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by david millar View Post
    Another thing : The Roofers have suggested that the wavy roof will come right in summer [ another 5 months away ] as tiles will heat and settle and the ply should straighten itself with heat ? , it is winter here now with frosts . I could`nt amagine ply straightening it`s self with heat ? But I`m no expert ! but I`m not a flamen idiot either !
    Quote Originally Posted by david millar View Post
    We havent paid for job done or materials yet [ on our lawyers advice ] what would you recommend we do ?
    I recommend you tell the contractor 'Okay, on your advice we will wait for summer to see how it looks, and, based on that advice we will also wait until the following winter to make sure it does not come back ... and if all is well at that time then we will pay you the remainder of the roof work cost.

    I seriously doubt that the contractor wants to wait a full year for payment on the hope that it will 'fix itself and not comeback next winter'.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Although the fault is showing up at the tiles 9shingles), I don't think the problem is with the tiles. They are simply a reflection of what is happening underneath. I doubt they will ever lay flat.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Have been told that plywood when installed on roof under tiles should have had a gap between edges so the plywood can move [ srink/expand ] around if required ? as I have said ours wasn`t it was hit tight together , in NZ there are no specs or requirements for council that states there should be a gap . Heres my question : in your country is it a spec requirement from your council that a gap has to be applied ?, thanks


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by david millar View Post
    Have been told that plywood when installed on roof under tiles should have had a gap between edges so the plywood can move [ srink/expand ] around if required ? as I have said ours wasn`t it was hit tight together , in NZ there are no specs or requirements for council that states there should be a gap . Heres my question : in your country is it a spec requirement from your council that a gap has to be applied ?, thanks
    when there is no spec from gov't, the manufacturer's specs are the rule.

    - - - Updated - - -

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Hello its me back again from NZ , well nothing has happened with roof since May house is still on hold !!! , and no the Roofers/Tilers/plywood contractor still havent been paid . They are trying to come to agreement amongst themselves who is liable and what is best way to fix roof ???
    My question to you experts is : do all shingle roofs in America look like this with wavy shodowing ? , been told here that this shadowing is the norm in US . If they [ contractors ] do decide to replace tiles and plywood what ply thickness would you recommend in this case with 900 mm truses ? would you use treated ply ? and are Black Morie Certainteed Tiles a good choice ? . Thanks again really apreciate your advice ! The reason I ask is that tile roofs in NZ and hardly ever used I was just silly enough to like them


  24. #24
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    The kind of waviness in your photo is neither common or considered acceptable in the two large markets where I have worked (Dallas and Denver). Although in very old houses, some wave in a roof is usually forgivable. Most of the roof decking that I see is 1/2" or 15/32" ply. I don't know about Black Morie shingles.

    If you choose not to decide, you still have made a choice.

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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by david millar View Post
    Hello its me back again from NZ , well nothing has happened with roof since May house is still on hold !!! , and no the Roofers/Tilers/plywood contractor still havent been paid . They are trying to come to agreement amongst themselves who is liable and what is best way to fix roof ???
    My question to you experts is : do all shingle roofs in America look like this with wavy shodowing ? , been told here that this shadowing is the norm in US . If they [ contractors ] do decide to replace tiles and plywood what ply thickness would you recommend in this case with 900 mm truses ? would you use treated ply ? and are Black Morie Certainteed Tiles a good choice ? . Thanks again really apreciate your advice ! The reason I ask is that tile roofs in NZ and hardly ever used I was just silly enough to like them


    David,
    Roofs in America do not look like that. The ones you see in posts to IN are the atypical/problem roofs.

    The deck should be 5/8 inch 5 ply or better with H-clips and 1/8 inch gap on buts over trusses with composition shingle.

    Treated plywood is not needed. Good CDX is what you need.

    As far as how/who will correct the problem and how/who will eat the costs involved will be the ultimate issue. Guys laying the shingle will say that the shingle was applied according to manf. install. instructions. They will say they did what they were supposed to do and the problem was with the deck and they are not responsible/liable. Even though when they went to lay the shingle they saw that the deck was installed incorrectly, if in fact they did, they might contend that they were there to lay shingle and not to inspect or criticize other peoples work. The guys that laid the deck are where the problem started with possibly some blame on the installers of the trusses. Now if the job was spected with the wrong plywood (deck) then it goes back to design/specifications.

    Ultimately like so many times no one wants to take responsibility or those who end up with responsibility want to mitigate the costs to correct.

    Being a new house and not knowing the contents of the contracts, you may be in some peril for completion under the contracts. I have seen the occasion where the cost may cause the builder to file bankruptcy because this was the problem that took him over the edge financially, or as a way to just bail on the project. Not wanting to be all doom and gloom, but make sure that you protect your position. When you start hearing that the trades are "trying to come to agreement amongst themselves who is liable and what is best way to fix roof ", its time to circle your wagons and be prepared for what may be coming.

    In the US subs will walkaway and put leans on the property that have to be settled before completion and the title can be transferred.


  26. #26
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Gidday Garry
    Thankyou for your advice . The contractors that installed the deck are the same 3 guys that layed the tiles ?
    They still saying that the shaddow effect is normal and all houses in America have this ! they also said that Ashfelt Tiles are the prefered roof material in America because they cheep and you pay for what you get ! [ Tiles in NZ are twice price other roofing material eg Colour Steel ]
    What other roofing Materials do you use Colour Steel , iron etc ?
    I really appreciate everyones feed back thankyou
    Like you said Garry I better start circling the wagons !
    Regards David
    Quote Originally Posted by Garry Sorrells View Post
    David,
    Roofs in America do not look like that. The ones you see in posts to IN are the atypical/problem roofs.

    The deck should be 5/8 inch 5 ply or better with H-clips and 1/8 inch gap on buts over trusses with composition shingle.

    Treated plywood is not needed. Good CDX is what you need.

    As far as how/who will correct the problem and how/who will eat the costs involved will be the ultimate issue. Guys laying the shingle will say that the shingle was applied according to manf. install. instructions. They will say they did what they were supposed to do and the problem was with the deck and they are not responsible/liable. Even though when they went to lay the shingle they saw that the deck was installed incorrectly, if in fact they did, they might contend that they were there to lay shingle and not to inspect or criticize other peoples work. The guys that laid the deck are where the problem started with possibly some blame on the installers of the trusses. Now if the job was spected with the wrong plywood (deck) then it goes back to design/specifications.

    Ultimately like so many times no one wants to take responsibility or those who end up with responsibility want to mitigate the costs to correct.

    Being a new house and not knowing the contents of the contracts, you may be in some peril for completion under the contracts. I have seen the occasion where the cost may cause the builder to file bankruptcy because this was the problem that took him over the edge financially, or as a way to just bail on the project. Not wanting to be all doom and gloom, but make sure that you protect your position. When you start hearing that the trades are "trying to come to agreement amongst themselves who is liable and what is best way to fix roof ", its time to circle your wagons and be prepared for what may be coming.

    In the US subs will walkaway and put leans on the property that have to be settled before completion and the title can be transferred.



  27. #27
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    The tile (shingle) quality/grade is not a factor in this installation.

    Metal roofs are a small percentage of the roof coverage market due to cost.. Typical roof is a 3 tab asphalt (composite) shingle or something similar.. In city applications there are a high percentage of built-up, flat, roof construction due to row/townhouse construction.

    Beware if "They still saying that the shaddow effect is normal and all houses in America have this". I would have to say they have absolutely no idea or basis for their assertion. By making that statement I would say they are just trying to blow smoke up your skirt. Granted I o not have any experience in NZ, but right is right and wrong is wrong.


  28. #28
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Your builder might be a friend and that was the mistake. You never mix family or friends with business or money.

    Next, please tell your builder and the installers of the sheathing and shingles that they are horses asses.

    I gorra tell you straight out. Your roof looks like crap and totaly unexceptable and this is house you must approach your builder/friend and roofers.

    Bring them to every neighborhood in the area. Show them the endless amount of non wavy roofs and then drive back to your new home and just point and stay silent. If they say the first word and the words are crap like yoou told us so far go talk to your lawyer and tell your friend and roofers you will see them in court.


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Gidday Ted
    Thanks for your advice
    To be fair the builder has been great , he too is pulling his hairout wanting a solution as the hole roof issue is holding up the build for him also [ as we stopped the build as soon as we seen shaddowing ] The Roofers were subbies that he was recommended by a large NZ building supply firm [ Mitre10 Mega ].
    The builder is also pissed as its his sign at the gate and hes been tarred with the hole balls-up
    You said about showing builder/roof around our neighbourhood trouble is no certainteed 3 Tab ashfelt shingles in our area , like I said earlier in NZ these tiles are not used, use mainly corrigated iron
    Thanks David
    Quote Originally Posted by Ted Menelly View Post
    Your builder might be a friend and that was the mistake. You never mix family or friends with business or money.

    Next, please tell your builder and the installers of the sheathing and shingles that they are horses asses.

    I gorra tell you straight out. Your roof looks like crap and totaly unexceptable and this is house you must approach your builder/friend and roofers.

    Bring them to every neighborhood in the area. Show them the endless amount of non wavy roofs and then drive back to your new home and just point and stay silent. If they say the first word and the words are crap like yoou told us so far go talk to your lawyer and tell your friend and roofers you will see them in court.



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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Has the manufacturer been contacted about the shingles? Have you sent them pictures for comment?

    Looking at the photo I am also wondering if these are defective shingles or seconds because there appears to be a lot of clawing on the ride side slope.

    Can you provide a few close ups of the shingles?


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    David,
    Metal roofs may be the crux of the problem. The metal roofs may be hiding the waivey roof deck on the other houses. If their work is hidden then all is good in their book.


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Gidday Im Back from NZ
    Well to say the sh-t has hit the fan in the last 6 months is a understatement !!!!
    Builders have agreed to pull tiles and plywood off roof and start again !!!
    They started yesterday but I need your advice urgently !
    They are using 17 mm Strandboard and they have got a 3mm gap around the sheets and the rafters are at 900mm Centres the problem is you can see the plywood across the spans is at different hights slightly [ approx 1 to 2 mm diff in spans ] .We are worried that when they put ashfelt 3 tab tiles ontop of ply [ same tiles as before new ] . You will see the deflections even worse at the joins in ply being different hights ?
    Have been looking on info about roof sheating and do you think we should be using h Clips between ply sheets ? As rafters are 900 mm apart
    Its bad enough having to take whole roof off but even worse if new roof looks worse than the first .
    Really appreciate your advice as this roofing [ 3 tab ashfelt tiles over ply ] is all new to NZ builders and I am having real trouble getting info
    Thanks for your advice in advance
    We have stopped the builders for doing anymore at moment untill we sort the saging out
    Kind Regards
    David


  33. #33
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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    If you are saying you can discern different plywood "heights" from the ground, something is not right:

    1. Are you too sensitized to the issues now, meaning it will be almost impossible to make you comfortable?
    2. Is all the decking material the same nominal thickness?
    3. Were the rafters absolutely bare (no debris, driven in nails, raised splinters, etc.) prior to deck installation?
    4. Did the decking material, Strandboard, get wet and swell or warp prior to installation?
    5. Are the installers using fasteners that are long enough to hold the materials tightly in contact with the rafters?

    You are absolutely correct to raise the issue now, but the contractors may not relent until an unacceptable appearance exists.


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    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    Quote Originally Posted by david millar View Post
    Gidday Im Back from NZ
    ...
    They are using 17 mm Strandboard and they have got a 3mm gap around the sheets and the rafters are at 900mm Centres the problem is you can see the plywood across the spans is at different hights slightly [ approx 1 to 2 mm diff in spans ] ........
    ........do you think we should be using h Clips between ply sheets ? As rafters are 900 mm apart

    David

    David,
    I have to apologize for not focusing on the rafters earlier. Here in the US we (old farts) do not think in mm (metric). Feet or inches and using fractions (1/2, 5/8, 3/4). So your 900mm just did not raise a flag.

    900mm is 35 7/8 inches. We set rafters on 16 inch or more typical 24 inch centers. So the span is a real concern for your roof. At 36inches I would not feel comfortable with anything less than 3/4 inch plywood.

    The 17mm Stranboard converts to OSB (Oriented Strand Board) 43/64inch (.6719inch) which is either a thin 3/4inch (.75inch) or a heavy 5/8inch ( .63inch). Either way at 17mm I would not begin to consider to use it on a roof deck. My preference is 5/8 inch 5 ply plywood exterior sheathing (CDX) on 24 inch center.. With the use of H-clips in-between the rafters. Additionally there should be a 1/8 inch spacing (gap) at the but on the rafters.

    The 1mm to 2mm (5/64inch, .078 inch)would not be a concern to me which is less than 1/8 inch variance (1/8 = .125).

    After making the conversions I can see how the roof became so wavy, especially after being rained on. Most OSB just does not stand up to water, which is why I just don't like it. Then add the 36inch on center truss to the reciepe for trouble.

    It may be typical for the other side of the equator and may work out on paper to be acceptable (even with a engineered stamp), but spanning the trusses at 36 inches (900mm) with anything less than 1 inch plywood seems like a problem. The roof may not collapse but it will look Butt Ugly.


    You might be able to go with the 17mm and triple the number of H-clips. But I would still have concerns.

    For the brethren who, like myself, may be metric challenged (or just refusing to convert) here are some metric to inch conversions.

    .MM........... Fractions ....... Dec .......... fracton = Dec
    900 ................35 7/16 ............................36 inch (3 feet)

    19 --------------- -------------.75 ------------- = .75

    17 -------------- 43/64--------- .6719 ----------- 5/8 = .63

    16 ----------------5/8 ------------.63 -------------- 5/8 = .63

    15 -------------- 19/32---------- .594 -------------- = .50

    13 -------------- 33/64 -----------.52---------------- = .50

    3 ---------------- 9/64 ------------.141-------------- 1/8 = .125

    2----------------- 5/64 ------------ .078

    1----------------- 3/64 -------------- .047 --------------- 1/16 = .063

    Materil Stamped --------Thought as -----------------Actual thinckness

    7/16 OSB-------------------- -------------------------- .44

    19/32 OSB------------------ 5/8 ----------------------------.59

    23/32 OSB ------------------- ------------------------------ .72

    Last edited by Garry Sorrells; 10-24-2013 at 07:58 AM.

  35. #35
    Join Date
    Mar 2007
    Location
    Plano, Texas
    Posts
    4,170

    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    You will never get a flat plane with relatively thin plywood or OSB with wide spacing of the rafters.
    Even H clips are of no great help on 36" centers. Either increase the thickness of the roof decking or reduce the spacing between rafters.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  36. #36
    Join Date
    Dec 2008
    Location
    Maryland
    Posts
    2,776

    Default Re: New Shingle Roof Installed looks like a wavy ocean ?

    The more the distance of the trusses setts into my mind other questions come to mind, "Peculation Principle".

    David,
    Was the OSB used originally and/or the new proposed 3600mm (141 47/64")? If not, them the lack of the deck not spanning over at least one truss would lead to the problems also. Add in any effort to reduce waste and use short pieces that only goes between two trusses will sag also.

    Also, is 900mm truss spacing the norm for the world Down Under?


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